JP2004200389A - Oxide semiconductor light emitting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an oxide semiconductor light emitting element that can form a reflection end face by a simple method and has improved optical characteristics and reliability. <P>SOLUTION: An n-type buffer layer 2, an n-type cladding layer 3, an n-type light guide layer 4, a non-doped quantum well active layer 5, a p-type light guide layer 6, a p-type cladding layer 7, and a p-type contact layer 8, are laminated on an n-type ZnO single-crystal substrate 1 with (1 -1 0 0) surface as a growth surface by a ZnO-based semiconductor. A ridge stripe in the direction of [1 1 -2 0] is formed on the contact layer 8 and the cladding layer 7. A (1 1 -2 0) surface vertical to the ridge stripe is subjected to cleavage to form a light reflection end face. As a result, by setting two mutually orthogonal easy cleavage surfaces that are easy cleavage surfaces to be the growth surface and the reflection end face, the reflection end face can be formed by simple cleavage. As a result, as compared with a comparison example where the reflection end face is formed by dry etching, an oscillation threshold current can be decreased by 30%, and element lifetime can be increased by five times. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an oxide semiconductor light emitting device having excellent optical characteristics and reliability.
[0002]
[Prior art]
Zinc oxide (ZnO) is a direct transition semiconductor having a band gap energy of about 3.4 eV, has an extremely high exciton binding energy of 60 meV, is inexpensive in raw materials, is harmless to the environment and the human body, and has a film forming method. Have features such as simplicity. In the following, the ZnO-based semiconductor includes ZnO and a mixed crystal represented by MgZnO, CdZnO or the like using the same as a host.
[0003]
Conventionally, it has been difficult to control the conductivity type of ZnO to p-type because of the self-compensation effect caused by strong ionicity. However, by using nitrogen (N) as an acceptor impurity, p-type is realized, and ZnO is realized. Many studies have been made to manufacture a highly efficient light-emitting element using a system semiconductor.
[0004]
Among them, the blue semiconductor laser device having an oscillation wavelength of around 400 nm is expected to be put to practical use, including application to a next-generation high-density light source for digital optical recording, and the blue semiconductor laser device is manufactured from a ZnO-based semiconductor. If it can be performed, there is a possibility that a light emitting device with higher efficiency, lower power consumption and more environmental friendliness than a blue semiconductor laser device using a group III nitride semiconductor which is currently in practical use can be realized.
[0005]
[Problems to be solved by the invention]
However, when a blue semiconductor laser device is manufactured using the ZnO-based semiconductor, there are the following problems.
[0006]
That is, in the semiconductor laser device, it is necessary to form a laser resonator having a pair of reflection end faces perpendicular to the extending direction of the waveguide. Since a GaAs / AlGaAs-based material or the like has a cleavage property, a flat reflection end face can be obtained at an atomic level. However, since the ZnO-based semiconductor is hexagonal, cleavage is more difficult than that of a cubic semiconductor. In particular, in a semiconductor laser device formed on a sapphire substrate, since the sapphire substrate has no cleavage property, a reflection end face has to be formed by a method such as dry etching.
[0007]
However, there is a problem that the flatness and parallelism of the reflection end face formed by etching are not good, and the characteristics are greatly inferior to those of the semiconductor laser device having the reflection end face formed by cleavage. Further, there is a problem that the manufacturing process becomes complicated and the cost increases.
[0008]
Accordingly, an object of the present invention is to provide an oxide semiconductor laser device that can form a reflection end face by a simple method and has excellent optical characteristics and reliability.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention relates to an oxide semiconductor light emitting device including a hexagonal ZnO based semiconductor layer formed on a ZnO substrate, wherein the growth surface of the ZnO substrate is (1-1100) , (0-11 0), (-1 10 10), (-1 10 0), (0 1-1 0), and (1 10-10) A waveguide is formed extending parallel to the direction of the junction surface of the ZnO-based semiconductor layer, and a pair of resonator end faces perpendicular to the extending direction of the waveguide are formed by cleavage. (11-20), (2-1-10), (1-210), (1-120), (2-110) and (-12-10) Any one of the following.
[0010]
According to the above configuration, a ZnO substrate most suitable for growing a ZnO-based semiconductor layer is used as a substrate material. Therefore, an oxide semiconductor laser device having extremely few crystal defects and lattice distortion is formed.
[0011]
The growth plane of the ZnO substrate is an M plane in a hexagonal system, and the cleavage plane is an A plane in a hexagonal system. The surface A is an easily cleaved surface and has extremely excellent flatness, and can be used as a reflection end surface. Further, since the A-plane is orthogonal to the M-plane, which is the growth plane, by forming the pair of resonator end faces by cleavage, the parallelism between the two reflection end faces becomes extremely high.
[0012]
Therefore, an oxide semiconductor laser device having excellent optical characteristics and reliability can be obtained.
[0013]
Further, the present invention is an oxide semiconductor light emitting device including a hexagonal ZnO-based semiconductor layer formed on a ZnO substrate, wherein the growth surface of the ZnO substrate is (1-100), (0-1). 10), (-1 0 10), (-1 1 10), (0 1-10), and (1 10-10), and each one is a junction of each ZnO-based semiconductor layer. The waveguide extends in parallel with the plane direction to form a waveguide, and a pair of resonator end faces perpendicular to the extending direction of the waveguide are formed by cleavage, and the cleavage plane is (0 0 0 1) And (0 0 -1).
[0014]
According to the above configuration, a ZnO substrate most suitable for growing a ZnO-based semiconductor layer is used as a substrate material. Therefore, an oxide semiconductor laser device having extremely few crystal defects and lattice distortion is formed.
[0015]
The growth plane of the ZnO substrate is an M plane in a hexagonal system, and the cleavage plane is a C plane in a hexagonal system. The C plane is an easily cleaved plane and has extremely excellent flatness, and can be used as a reflection end face. Further, since the C plane is orthogonal to the M plane, which is the growth plane, the parallelism between the two reflection end faces becomes extremely high by forming the pair of resonator end faces by cleavage.
[0016]
Therefore, an oxide semiconductor laser device having excellent optical characteristics and reliability can be obtained.
[0017]
Further, the present invention is an oxide semiconductor light emitting device including a hexagonal ZnO-based semiconductor layer formed on a ZnO substrate, wherein the growth surface of the ZnO substrate is (11-20), (2-1). -10), (1-210), (-1-120), (-2110) and (-12-10), and each ZnO-based A waveguide is formed extending parallel to the direction of the bonding surface of the semiconductor layer, and a pair of resonator end faces perpendicular to the extending direction of the waveguide are formed by cleavage. -1 100), (0-1 10), (-1 10 10), (-1 10 0), (0 1-10), and (1 0-10) I have.
[0018]
According to the above configuration, a ZnO substrate most suitable for growing a ZnO-based semiconductor layer is used as a substrate material. Therefore, an oxide semiconductor laser device having extremely few crystal defects and lattice distortion is formed.
[0019]
The growth plane of the ZnO substrate is the A plane in the hexagonal system, and the cleavage plane is the M plane in the hexagonal system. The M plane is an easily cleaved plane and has extremely excellent flatness, and can be used as a reflection end face. Further, since the M plane is orthogonal to the A plane, which is the growth plane, the parallelism between the two reflection end faces is extremely high by forming the pair of resonator end faces by cleavage.
[0020]
Therefore, an oxide semiconductor laser device having excellent optical characteristics and reliability can be obtained.
[0021]
Further, the present invention is an oxide semiconductor light emitting device including a hexagonal ZnO-based semiconductor layer formed on a ZnO substrate, wherein the growth surface of the ZnO substrate is (11-20), (2-1). -10), (1-210), (-1-120), (-2110) and (-12-10), and each ZnO-based A waveguide is formed extending parallel to the direction of the bonding surface of the semiconductor layer, and a pair of resonator end faces perpendicular to the extending direction of the waveguide are formed by cleavage. 001) and (0000-1).
[0022]
According to the above configuration, a ZnO substrate most suitable for growing a ZnO-based semiconductor layer is used as a substrate material. Therefore, an oxide semiconductor laser device having extremely few crystal defects and lattice distortion is formed.
[0023]
The growth plane of the ZnO substrate is the A plane in the hexagonal system, and the cleavage plane is the C plane in the hexagonal system. The C plane is an easily cleaved plane and has extremely excellent flatness, and can be used as a reflection end face. Furthermore, since the C plane is orthogonal to the A plane, which is the growth plane, the parallelism between the two reflection end faces is extremely high by forming the pair of resonator end faces by cleavage.
[0024]
Therefore, an oxide semiconductor laser device having excellent optical characteristics and reliability can be obtained.
[0025]
Further, the present invention is an oxide semiconductor light emitting device including a hexagonal ZnO-based semiconductor layer formed on a ZnO substrate, wherein the growth surface of the ZnO substrate is (0 0 0 1) and (0 0 0- As any one of 1), a waveguide is formed extending in parallel with the direction of the bonding surface of each ZnO-based semiconductor layer, and a pair of resonator end faces perpendicular to the extending direction of the waveguide are cleaved. And the cleavage planes are defined as (1-1 0 0), (0-1 10), (-1 0 1 0), (-1 1 0 0), (0 1-10) and (10-10).
[0026]
According to the above configuration, a ZnO substrate most suitable for growing a ZnO-based semiconductor layer is used as a substrate material. Therefore, an oxide semiconductor laser device having extremely few crystal defects and lattice distortion is formed.
[0027]
The growth plane of the ZnO substrate is a C plane in a hexagonal system, and the cleavage plane is an M plane in a hexagonal system. The M plane is an easily cleaved plane and has extremely excellent flatness, and can be used as a reflection end face. Further, since the M plane is orthogonal to the C plane which is the growth plane, the parallelism between the two reflection end faces is extremely high by forming the pair of resonator end faces by cleavage.
[0028]
Therefore, an oxide semiconductor laser device having excellent optical characteristics and reliability can be obtained.
[0029]
Further, the present invention is an oxide semiconductor light emitting device including a hexagonal ZnO-based semiconductor layer formed on a ZnO substrate, wherein the growth surface of the ZnO substrate is (0 0 0 1) and (0 0 0- 1), forming a waveguide extending in parallel with the direction of the bonding surface of each ZnO-based semiconductor layer, and cleaving a pair of resonator end faces perpendicular to the extending direction of the waveguide. And the cleavage planes are defined as (1 1-2 0), (2-1-10), (1-2 10), (1-1 12 0), (-2 11 10). ) And (-1 2-10).
[0030]
According to the above configuration, a ZnO substrate most suitable for growing a ZnO-based semiconductor layer is used as a substrate material. Therefore, an oxide semiconductor laser device having extremely few crystal defects and lattice distortion is formed.
[0031]
The growth plane of the ZnO substrate is a C plane in a hexagonal system, and the cleavage plane is an A plane in a hexagonal system. The surface A is an easily cleaved surface and has extremely excellent flatness, and can be used as a reflection end surface. Further, since the A-plane is orthogonal to the C-plane, which is the growth plane, by forming the pair of resonator end faces by cleavage, the parallelism between the two reflection end faces becomes extremely high.
[0032]
Therefore, an oxide semiconductor laser device having excellent optical characteristics and reliability can be obtained.
[0033]
In the oxide semiconductor light emitting device of one embodiment, the main growth surface of the ZnO substrate has an inclination of 15 ° or less from the growth surface.
[0034]
According to this embodiment, an "off substrate" inclined from the growth surface is used as the ZnO substrate. In such an “off-substrate”, since steps and terraces are formed on the main growth surface, “step flow growth” in which material atoms are taken in steps and two-dimensionally grow, is likely to occur. Therefore, a ZnO-based semiconductor layer having excellent flatness can be obtained, and an oxide semiconductor light-emitting element having excellent luminous efficiency and reliability can be manufactured.
[0035]
Further, the oxide semiconductor light emitting device of one embodiment includes a multilayer reflective film formed in contact with the cleavage plane and formed by laminating a plurality of inorganic material thin films having different refractive indexes.
[0036]
According to this embodiment, a multilayer reflection film formed by laminating a plurality of inorganic material thin films is formed on a cleavage reflection end face from which laser light is emitted. By doing so, the reflectance can be controlled by the number of layers of the inorganic material thin film, and the effect of protection from a reducing atmosphere can be enhanced. Therefore, excellent reliability can be obtained even for long-time driving.
[0037]
Further, in the oxide semiconductor light emitting device of one embodiment, each of the multilayer reflective films formed on the pair of cleavage planes has a different reflectance.
[0038]
According to this embodiment, one of the pair of cleavage planes has a high reflectivity and the other has a low reflectivity, thereby suppressing loss and improving light emission efficiency. Is done.
[0039]
In the oxide semiconductor light emitting device of one embodiment, the reflectance of each of the multilayer reflective films formed on the pair of cleavage planes is 5% or more and 95% or less.
[0040]
According to this embodiment, the reflectivity of the multilayer reflective film at one of the pair of cleavage planes is set to 5% or more and 35% or less at which a sufficient light output is ensured, while the reflectivity of the multilayer reflective film at the other is set. Can be set to 70% or more and 95% or less which can secure a sufficient reflectance. Thus, an oxide semiconductor laser device having more excellent optical characteristics and reliability can be obtained.
[0041]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.
[0042]
FIG. 4 is a schematic diagram illustrating a crystal structure of a hexagonal ZnO-based semiconductor. The ZnO-based semiconductor has a C-plane, an M-plane, and an A-plane as easy cleavage planes, which are orthogonal to each other. That is, by selecting any two of these three surfaces as the crystal growth surface and the cleavage reflection end surface, it becomes possible to realize an oxide semiconductor laser device having excellent characteristics.
[0043]
・ First embodiment
FIG. 1 is a perspective view showing a structure of a ZnO based semiconductor laser device 13 which is an example of the oxide semiconductor light emitting device of the present embodiment. FIG. 2 is a side view.
[0044]
The present ZnO-based semiconductor laser device 13 has a Ga doping concentration of 1 × 10 4 on an n-type ZnO single crystal substrate 1 having a (1-1100) plane as a growth surface. ¹⁸ cm ^-3 N-type ZnO buffer layer 2 having a thickness of 0.1 μm and a Ga doping concentration of 3 × 10 ¹⁸ cm ^-3 N-type Mg with 1μm thickness _0.1 Zn _0.9 O cladding layer 3, Ga doping concentration 5 × 10 ¹⁷ cm ^-3 30 nm thick n-type ZnO light guide layer 4, non-doped quantum well active layer 5, N doping concentration of 1 × 10 ¹⁸ cm ^-3 P-type ZnO light guide layer 6 having a thickness of 30 nm and an N doping concentration of 5 × 10 ¹⁹ cm ^-3 1.2μm thick p-type Mg _0.1 Zn _0.9 O clad layer 7, N doping concentration 1 × 10 ²⁰ cm ^-3 A p-type ZnO contact layer 8 having a thickness of 0.5 μm is sequentially laminated.
[0045]
The quantum well active layer 5 includes two ZnO barrier layers each having a thickness of 5 nm and Cd having a thickness of 6 nm. _0.1 Zn _0.9 It is configured by alternately stacking three O well layers. Further, the p-type ZnO contact layer 8 and the p-type Mg _0.1 Zn _0.9 The O-cladding layer 7 is etched in the form of a ridge stripe in the [11-20] direction. ¹⁸ cm ^-3 -Type Mg doped at a concentration of _0.2 Zn _0.8 It is buried by the O current block layer 9.
[0046]
On the lower surface of the n-type ZnO single crystal substrate 1, an n-type ohmic electrode 10 is formed, and a p-type ZnO contact layer 8 and an n-type Mg _0.2 Zn _0.8 On the upper surface of the O current block layer 9, a p-type ohmic electrode 11 is formed.
[0047]
Further, the light reflecting end face forming the optical resonator is formed by cleaving the (11-20) plane perpendicular to the extending direction [11-20] of the ridge stripe. On the reflecting surface, a 60 nm thick MgO layer 12a and a 70 nm thick SiO _Two The multilayer reflective film 12 is formed by alternately stacking layers 12b. At this time, each of the multilayer reflective films 12 has a reflectivity for light having a wavelength of 405 nm of 30% for one (front) light reflective surface and 95% for the other (rear) light reflective surface. MgO layer 12a and SiO2 _Two The number of layers with the layer 12b is adjusted.
[0048]
The present embodiment is characterized in that the M-plane and the A-plane among the three orthogonal C-planes, the M-planes and the A-planes, which are easy cleavage planes in the ZnO-based semiconductor, are used as the growth plane and the light reflection end face. have.
[0049]
When a current was applied to the ZnO-based semiconductor laser device 13 in the present embodiment, blue oscillation light having a wavelength of 405 nm was obtained from the cleavage reflection end face. In this case, the oscillation threshold current was 40 mA, and the element life (defined as the time when the operating current was increased by 20% from the initial value by continuous oscillation at 60 ° C. and an optical output of 5 mW) was 10,000 hours.
[0050]
As a comparative example, a ZnO-based semiconductor laser device in which the light reflecting end face was formed by dry etching instead of cleavage was prepared. In that case, the oscillation threshold current was increased by 30%, and the device life was reduced to 1/5, that is, 2,000 hours.
[0051]
As described above, in the ZnO-based semiconductor laser device 13 according to the present embodiment, a ZnO substrate most suitable for growing a ZnO-based semiconductor layer is used as a substrate material. Therefore, an oxide semiconductor laser device having extremely few crystal defects and lattice distortion is formed. Further, since the light reflecting end face is formed by cleavage, the flatness, the perpendicularity, and the parallelism are excellent. Therefore, the characteristics can be improved as compared with the ZnO-based semiconductor laser device of the comparative example in which the light reflecting end face is formed by dry etching.
[0052]
FIG. 3 shows the substrate off-angle and the substrate off angle when a ZnO-based semiconductor laser device similar to the ZnO-based semiconductor laser device 13 was manufactured using a ZnO single-crystal substrate having various inclinations with respect to the (1-1100) plane. This shows the relationship with the emission intensity. The emission intensity in FIG. 3 is obtained by driving the ZnO-based semiconductor laser device at 20 mA which is equal to or less than the oscillation threshold current, and comparing the intensity of the spontaneous emission light.
[0053]
According to FIG. 3, the emission intensity increases up to the off angle of 15 ° as compared with the “just substrate” having no inclination, and the emission intensity sharply decreases when the off angle exceeds 15 °. That is, it is understood that it is preferable to use an “off substrate” whose growth surface has an inclination of 15 ° or less.
[0054]
As described above, the reason why the emission intensity is increased when the “off substrate” is used is that “step flow growth” occurs in which material atoms are incorporated into steps and two-dimensionally grow, and the crystallinity and flatness of the ZnO-based semiconductor layer are increased. In particular, it is considered that an off-substrate having an inclination angle of up to 15 ° has an excellent flatness of a grown layer because of having an appropriate step height and a wide terrace. Can be
[0055]
As described in the present embodiment, light emission efficiency can be improved by making one end face of the semiconductor laser element highly reflective and making the other end face low reflection. In addition, by covering the end face with the multilayer reflective film 12, which is an oxide multilayer film, not only can the ZnO-based semiconductor laser device 13 be protected from a reducing atmosphere, but also the reflectance can be controlled by the number of stacked layers, and the reflection loss can be reduced. As a result, the oscillation threshold current is reduced, and a ZnO-based semiconductor laser device 13 having excellent reliability can be manufactured.
[0056]
As for the end face reflectivity of the semiconductor laser element, if the reflectivity of one end face (front face) is 5% to 35%, a sufficient light output can be secured, and the reflectivity of the other end face (rear face) is 70%. % Or more, a sufficient reflectance can be secured. However, when the light output from the rear surface is detected by a light receiving element (not shown) in order to monitor the light output of the semiconductor laser device, it is preferable that the reflectance of the rear surface be 90% or less.
[0057]
・ Second embodiment
In the present embodiment, the ridge stripe is formed in the [0 0 0 1] direction, and the (0 0 1) plane perpendicular to the extending direction of the ridge stripe is cleaved to form the light reflection end face. Manufactures a ZnO-based semiconductor laser device in the same manner as in the first embodiment.
[0058]
That is, in the present embodiment, the M-plane and the C-plane among the three C-planes, M-planes, and A-planes, which are easy cleavage planes in the hexagonal ZnO-based semiconductor, are used as the growth plane and the reflection end plane. Things.
[0059]
When a current was applied to the ZnO-based semiconductor laser device in the present embodiment, blue oscillation light having a wavelength of 410 nm was obtained from the cleavage reflection end face. In this case, the oscillation threshold current and the device life were 40 mA and 10,000 hours as in the first embodiment.
[0060]
・ Third embodiment
In this embodiment, a (11-20) plane of a ZnO single crystal substrate is used as a growth surface, a ridge stripe is formed in a [1-1100] direction, and the ridge stripe is perpendicular to the extending direction of the ridge stripe. A ZnO-based semiconductor laser device is manufactured in the same manner as in the first embodiment except that the light reflecting end face is formed by cleaving the (1-1100) plane.
[0061]
That is, in the present embodiment, the A-plane and the M-plane among the three C-planes, the M-planes, and the A-planes, which are easy cleavage planes, in the hexagonal ZnO-based semiconductor are defined as the growth plane and the reflection end face. Things.
[0062]
When a current was applied to the ZnO-based semiconductor laser device in the present embodiment, blue oscillation light having a wavelength of 410 nm was obtained from the cleavage reflection end face. In this case, the oscillation threshold current and the device life were 40 mA and 10,000 hours as in the first embodiment.
[0063]
-Fourth embodiment
In the present embodiment, the ridge stripe is formed in the [0 0 0 1] direction, and the (0 0 1) plane perpendicular to the extending direction of the ridge stripe is cleaved to form the light reflection end face. Manufactures a ZnO-based semiconductor laser device in the same manner as in the third embodiment.
[0064]
That is, in the present embodiment, the A-plane and the C-plane among the three C-planes, M-planes, and A-planes, which are easy cleavage planes in the hexagonal ZnO-based semiconductor, are defined as the growth plane and the reflection end face. Things.
[0065]
When a current was applied to the ZnO-based semiconductor laser device in the present embodiment, blue oscillation light having a wavelength of 410 nm was obtained from the cleavage reflection end face. In this case, the oscillation threshold current and the device life were 40 mA and 10,000 hours as in the first embodiment.
[0066]
-Fifth embodiment
In the present embodiment, a (0 0 1) plane of a ZnO single crystal substrate is used as a growth surface, a ridge stripe is formed in the [11-20] direction, and the ridge stripe is perpendicular to the extending direction of the ridge stripe. A ZnO-based semiconductor laser device is manufactured in the same manner as in the first embodiment except that the light reflecting end surface is formed by cleaving the (11-20) plane.
[0067]
That is, in the present embodiment, the C-plane and the A-plane among the three C-planes, M-planes, and A-planes which are easy cleavage planes in the hexagonal ZnO-based semiconductor are defined as the growth plane and the reflection end face. Things.
[0068]
When a current was applied to the ZnO-based semiconductor laser device in the present embodiment, blue oscillation light having a wavelength of 410 nm was obtained from the cleavage reflection end face. In this case, the oscillation threshold current and the device life were 40 mA and 10,000 hours as in the first embodiment.
[0069]
-Sixth embodiment
In the present embodiment, the ridge stripe is formed in the [1-1100] direction, and the light reflecting end face is formed by cleaving the (1-1100) plane perpendicular to the extending direction of the ridge stripe. Except for this, a ZnO-based semiconductor laser device is manufactured in the same manner as in the fifth embodiment.
[0070]
That is, in the present embodiment, the C-plane and the M-plane among the three C-planes, M-planes, and A-planes, which are easy cleavage planes in the hexagonal ZnO-based semiconductor, are defined as the growth plane and the reflection end face. Things.
[0071]
When a current was applied to the ZnO-based semiconductor laser device in the present embodiment, blue oscillation light having a wavelength of 410 nm was obtained from the cleavage reflection end face. In this case, the oscillation threshold current and the device life were 40 mA and 10,000 hours as in the first embodiment.
[0072]
In each of the above-described embodiments, the (1-1100) plane is exemplified as the M plane in the hexagonal ZnO-based semiconductor, but the (0-11) plane and the (-1010) plane. ) Plane, (-1 110) plane, (0 1-10) plane, or (10-10) plane may be used. Although the (1-120) plane is illustrated as the A plane, the (2-1-10) plane, the (1-210) plane, the (1-1-12) plane, The use of the (−211 0) plane and the (−1 2-10) plane does not matter. In addition, although the (0 00 1) plane is exemplified as the C plane, the (0 0 0-1) plane can be used without any problem.
[0073]
【The invention's effect】
As is clear from the above, the oxide semiconductor light emitting device of the present invention uses a ZnO substrate most suitable for growing a ZnO-based semiconductor layer as a substrate material. Therefore, an oxide semiconductor laser device having extremely few crystal defects and lattice distortion can be obtained.
[0074]
Further, the growth surface of the ZnO substrate is an M-plane in a hexagonal system, and a pair of resonator end faces is an A-plane orthogonal to the M-plane. Therefore, the cavity facet can be formed by cleaving the face A, which is an easy cleavage plane, and the flatness of the light reflection facet can be greatly improved as compared with the case where it is formed by etching. In this case, the cleavage plane A is perpendicular to the bonding plane direction parallel to the M plane. Therefore, the parallelism between the two reflection end faces can be extremely increased.
[0075]
The oxide semiconductor light-emitting device of the present invention uses a ZnO substrate most suitable for growing a ZnO-based semiconductor layer as a substrate material. Therefore, an oxide semiconductor laser device having extremely few crystal defects and lattice distortion can be obtained.
[0076]
Further, the growth plane of the ZnO substrate is an M plane in a hexagonal system, and a pair of resonator end faces is a C plane orthogonal to the M plane. Therefore, the cavity end face can be formed by cleaving the C-plane, which is an easy cleavage plane, and the flatness of the light reflection end face can be greatly improved as compared with the case where it is formed by etching. In that case, the C plane, which is the cleavage plane, is perpendicular to the bonding plane direction parallel to the M plane. Therefore, the parallelism between the two reflection end faces can be extremely increased.
[0077]
The oxide semiconductor light-emitting device of the present invention uses a ZnO substrate most suitable for growing a ZnO-based semiconductor layer as a substrate material. Therefore, an oxide semiconductor laser device having extremely few crystal defects and lattice distortion can be obtained.
[0078]
Further, the growth surface of the ZnO substrate is an A-plane in a hexagonal system, and a pair of resonator end faces is an M-plane orthogonal to the A-plane. Therefore, the cavity end face can be formed by cleaving the M-plane, which is an easy cleavage plane, and the flatness of the light reflection end face can be greatly improved as compared with the case where it is formed by etching. In that case, the M plane, which is the cleavage plane, is perpendicular to the bonding plane direction parallel to the A plane. Therefore, the parallelism between the two reflection end faces can be extremely increased.
[0079]
The oxide semiconductor light-emitting device of the present invention uses a ZnO substrate most suitable for growing a ZnO-based semiconductor layer as a substrate material. Therefore, an oxide semiconductor laser device having extremely few crystal defects and lattice distortion can be obtained.
[0080]
Further, the growth surface of the ZnO substrate is an A-plane in a hexagonal system, and a pair of resonator end faces is a C-plane orthogonal to the A-plane. Therefore, the cavity end face can be formed by cleaving the C-plane, which is an easy cleavage plane, and the flatness of the light reflection end face can be greatly improved as compared with the case where it is formed by etching. In this case, the C plane, which is the cleavage plane, is perpendicular to the bonding plane direction parallel to the A plane. Therefore, the parallelism between the two reflection end faces can be extremely increased.
[0081]
The oxide semiconductor light-emitting device of the present invention uses a ZnO substrate most suitable for growing a ZnO-based semiconductor layer as a substrate material. Therefore, an oxide semiconductor laser device having extremely few crystal defects and lattice distortion can be obtained.
[0082]
Further, the growth surface of the ZnO substrate is a C-plane in a hexagonal system, and a pair of resonator end faces is an A-plane orthogonal to the C-plane. Therefore, the cavity facet can be formed by cleaving the face A, which is an easy cleavage plane, and the flatness of the light reflection facet can be greatly improved as compared with the case where it is formed by etching. In that case, the cleavage plane A plane is perpendicular to the bonding plane direction parallel to the C plane. Therefore, the parallelism between the two reflection end faces can be extremely increased.
[0083]
The oxide semiconductor light-emitting device of the present invention uses a ZnO substrate most suitable for growing a ZnO-based semiconductor layer as a substrate material. Therefore, an oxide semiconductor laser device having extremely few crystal defects and lattice distortion can be obtained.
[0084]
Further, the growth surface of the ZnO substrate is a C-plane in a hexagonal system, and a pair of resonator end faces is an M-plane orthogonal to the C-plane. Therefore, the cavity end face can be formed by cleaving the M-plane, which is an easy cleavage plane, and the flatness of the light reflection end face can be greatly improved as compared with the case where it is formed by etching. In that case, the M plane, which is the cleavage plane, is perpendicular to the bonding plane direction parallel to the C plane. Therefore, the parallelism between the two reflection end faces can be extremely increased.
[0085]
That is, according to each of the above inventions, a reflection end face having excellent flatness and parallelism can be formed by a simple method of cleavage, and an oxide semiconductor laser element excellent in optical characteristics and reliability is provided. You can do it.
[0086]
If the growth main surface of the ZnO substrate is an “off substrate” having an inclination of 15 ° or less from the growth surface, a ZnO-based semiconductor layer having excellent flatness can be obtained, and further, luminous efficiency and reliability can be improved. Thus, it is possible to provide an oxide semiconductor light emitting device excellent in the above.
[Brief description of the drawings]
FIG. 1 is a perspective view of a ZnO-based semiconductor laser device which is an example of an oxide semiconductor light emitting device of the present invention.
FIG. 2 is a side view of the ZnO-based semiconductor laser device shown in FIG.
FIG. 3 is a diagram showing a relationship between an off-angle and a light emission intensity when a ZnO single crystal substrate having an inclination with respect to a (1-1100) plane is used.
FIG. 4 is a schematic diagram illustrating a crystal structure of a hexagonal ZnO-based semiconductor.
[Explanation of symbols]
1. n-type ZnO single crystal substrate,
2 ... n-type ZnO buffer layer,
3 ... n-type Mg _0.1 Zn _0.9 O clad layer,
4 ... n-type ZnO light guide layer,
5 ... non-doped quantum well active layer,
6 ... p-type ZnO light guide layer,
7 ... p-type Mg _0.1 Zn _0.9 O clad layer,
8 ... p-type ZnO contact layer,
9 ... n-type Mg _0.2 Zn _0.8 O current blocking layer,
10 ... n-type ohmic electrode,
11 ... p-type ohmic electrode,
12a ... MgO layer,
12b ... SiO _Two layer,
12 ... multilayer reflective film,
13. ZnO-based semiconductor laser device.

Claims (10)

An oxide semiconductor light emitting device including a hexagonal ZnO-based semiconductor layer formed on a ZnO substrate,
The growth surfaces of the ZnO substrate are (1-1 0 0), (0-1 10), (-1 10 0), (-1 1 10), (0 1-10) and (1 1 0). 0-10), and
A waveguide is formed extending parallel to the direction of the bonding surface of each ZnO-based semiconductor layer,
A pair of resonator end faces perpendicular to the extending direction of the waveguide are formed by cleavage,
The cleavage planes are (1-120), (2-1-10), (1-210), (1-120), (-2110), and (-1120). 2-10) An oxide semiconductor light-emitting device according to any one of the above items. An oxide semiconductor light emitting device including a hexagonal ZnO-based semiconductor layer formed on a ZnO substrate,
The growth surfaces of the ZnO substrate are (1-1 0 0), (0-1 10), (-1 10 0), (-1 1 10), (0 1-10) and (1 1 0). 0-10), and
A waveguide is formed extending parallel to the direction of the bonding surface of each ZnO-based semiconductor layer,
A pair of resonator end faces perpendicular to the extending direction of the waveguide are formed by cleavage,
The oxide semiconductor light-emitting device, wherein the cleavage plane is one of (000-1) and (000-1). An oxide semiconductor light emitting device including a hexagonal ZnO-based semiconductor layer formed on a ZnO substrate,
The growth surface of the ZnO substrate includes (1-120), (2-1-10), (1-210), (1-120), (2-110) and (-1 2-10), and
A waveguide is formed extending parallel to the direction of the bonding surface of each ZnO-based semiconductor layer,
A pair of resonator end faces perpendicular to the extending direction of the waveguide are formed by cleavage,
The cleavage planes are (1-1-100), (0-11), (-1010), (-1110), (01-10), and (10-1). 0) An oxide semiconductor light emitting device, which is any one of the above. An oxide semiconductor light emitting device including a hexagonal ZnO-based semiconductor layer formed on a ZnO substrate,
The growth surface of the ZnO substrate includes (1-120), (2-1-10), (1-210), (1-120), (2-110) and (-1 2-10), and
A waveguide is formed extending parallel to the direction of the bonding surface of each ZnO-based semiconductor layer,
A pair of resonator end faces perpendicular to the extending direction of the waveguide are formed by cleavage,
The oxide semiconductor light-emitting device, wherein the cleavage plane is one of (000-1) and (000-1). An oxide semiconductor light emitting device including a hexagonal ZnO-based semiconductor layer formed on a ZnO substrate,
The growth surface of the ZnO substrate is any one of (0 0 0 1) and (0 0 0-1),
A waveguide is formed extending parallel to the direction of the bonding surface of each ZnO-based semiconductor layer,
A pair of resonator end faces perpendicular to the extending direction of the waveguide are formed by cleavage,
The cleavage planes are (1-1-100), (0-11), (-1010), (-1110), (01-10), and (10-1). 0) An oxide semiconductor light emitting device, wherein the device is any one of the above. An oxide semiconductor light emitting device including a hexagonal ZnO-based semiconductor layer formed on a ZnO substrate,
The growth surface of the ZnO substrate is any one of (0 0 0 1) and (0 0 0-1),
A waveguide is formed extending parallel to the direction of the bonding surface of each ZnO-based semiconductor layer,
A pair of resonator end faces perpendicular to the extending direction of the waveguide are formed by cleavage,
The cleavage planes are (1-120), (2-1-10), (1-210), (1-120), (-2110), and (-1120). 2-10) An oxide semiconductor light-emitting device, which is any one of the above items. The oxide semiconductor light emitting device according to any one of claims 1 to 6,
An oxide semiconductor light emitting device, wherein a main growth surface of the ZnO substrate has an inclination of 15 ° or less from the growth surface. The oxide semiconductor light emitting device according to any one of claims 1 to 6,
An oxide semiconductor light emitting device comprising: a multilayer reflective film formed in contact with the cleavage plane and formed by laminating a plurality of inorganic material thin films having different refractive indexes. The oxide semiconductor light emitting device according to claim 8,
An oxide semiconductor light emitting device, wherein each of the multilayer reflective films formed on the pair of cleavage planes has a different reflectance. The oxide semiconductor light emitting device according to claim 8, wherein
An oxide semiconductor light emitting device, wherein the reflectivity of each multilayer reflective film formed on the pair of cleavage planes is 5% or more and 95% or less.

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